This invention relates generally to terminal boxes for electric motors and, more particularly, to terminal boxes which are mounted directly on an exterior surface of a motor housing.
Electric motors often have terminal boxes which house the connections between lead wires from the motor and feed wires from a source of electricity. The terminal boxes are generally mounted directly to an exterior surface of a motor housing. Typically, the terminal box comprises a base and a removable cover which gives an electrician easy access to the interior of the terminal box. In many such terminal boxes, the base includes a flat perimeter flange which extends around and projects outwardly from the top edges of the sidewalls of the base, and the cover has a corresponding flat perimeter flange which mates with the flange of the base when the terminal box is closed. Typically, the flanges are connected to one another with mechanical fasteners. In some prior art terminal boxes, a gasket is disposed between the flanges to help prevent water, oil or coolant from getting into the interior of the terminal box.
A problem with many of these prior art terminal boxes is that the flat mating surfaces of the flanges fail to provide a leak-proof seal, especially where the metal used for the terminal box is of a relatively thin gauge. Even where gaskets are used between the flat flanges, liquids are permitted to "wick" in because the seal may not be sufficiently tight. Where a thin gauge metal is used for the terminal box, the problem cannot be solved by simply tightening the mechanical fasteners which hold the flanges to one another, because over-tightening may tend to deform the thin gauge flanges and exacerbate the leakage problem.